Gas lasers, in particular CO2 lasers, can include a folded, preferably quadratic laser resonator in which the laser beam is folded quadratically in one or more parallel planes lying one above the other, and in which mirror elements, usually housed in four corner housings, are arranged in each plane. Discharge tubes with electrodes for exciting the laser gas are arranged between the corner housings. The laser gas is fed from a pressure source, which may be in the form, for example, of a radial fan, by feed lines to the corner housings. One or more cooling channels of a heat exchanger circuit are typically arranged in the feed lines to cool down the laser gas prior to entry into the corner housings and hence into the beam guidance chamber. The laser gas circulation path is closed by way of suction lines, by which the heated laser gas is extracted from the discharge tubes and fed to the radial fan.
The corner housings are usually cooled. For that purpose one or more cooling channels though which a cooling fluid, typically water, flows are arranged in a main body of a corresponding corner housing. The cooling channels of the heat exchanger circuit are generally connected to cooling channels of the corner housing and form a common coolant circuit.
With the above-described gas lasers, in particular where resonator lengths are long, a problem can arise where the laser beam undergoes an undesirable change in laser beam direction (in which the change in beam direction is known as beam pointing) in the laser resonator, which may lead to a deterioration of the beam quality.